The invention comprises a self-contained ultrasonic intrusion detector-transceiver including novel means adjustable to aim and project and create wave patterns to different areas to be monitored and to receive the echo waves. When the pattern area is penetrated, as by an intruder, some of the standing pattern waves are reflected; a "doppler" shift occurs, proportional to the motion of the intrusion source; the receiver senses the doppler shift and signals an alarm via a relay wired into the protective circuit of the alarm system; the unit works from a house current outlet through a plug-in transformer and rechargeable battery. With the unit cover in place, location of the area pattern coverage is undetectable whereas, in conventional detector units, the position of the unit discloses and betrays the pattern area monitored thereby. In contrast, one who views the unit of the invention with its cover on, as in normal operation, cannot detect the path or orienting and aiming of the transducers and therefore the monitored wave pattern areas for which they are set.
One form of unit has a single set or pair of transmitting and receiving transducers, adjustable to precisely aim them to a target area pattern desired. In the form of the invention having two sets of transmitters and receivers, each set is adjustable to point or aim a different direction; both sets feed into the same electronic circuitry; thus with only one electronic unit of the invention, sets of "doppler" shifts are separately received and processed. One may position one unit on the wall or other support and point one set of transducer transmitters-receivers at one target area and point the other set of transducer transmitter receivers in a different direction, at another target area. Each pair of transducer transmitter-receivers, thus independently aimable, may cover an infinite variety of protective pattern areas, such as separate, angular and odd-shaped rooms and areas, corners, hallways, "L" shaped rooms, "T" shaped halls, etc. (FIGS. 8-12).
Further advantages of the single unit form of this invention with two adjustable sets of transducer transmitters-receivers, compared with two conventional, separate units, each with a single set of fixed transducer transmitters-receivers, are that the cost of two of such conventional units is double the cost of one, and more wall space is required for such two separate units; also, two separate outlets are required.
The motion detector unit of the invention generates waves of predetermined ultrasonic wave length which are transmitted to walls or other target areas, the echos being returned to the receivers and thereby to a piezoelectric or other sensor converting the precalculated ultrasonic wave stress or pressure on the piezoelectric crystal oscillator into an electric charge, tripping a set of dry contacts of a relay, closing a circuit to a control unit and/or an on-premises alarm, triggering alarms such as a bull horn, bell, etc. Once the movement stops the alarm relay locks up another circuit, which will not reset until released, as by a key turned by the unit owner or operator. The alarm systems thus triggered may be audible, visible, and/or of message transmitting form, and may be connected to printout, radio, audio, etc. stations and units, to alert, for example, monitoring stations, such as monitoring police stations and vehicles, closed circuit TV screens, etc.
A typical conventional ultrasonic motion detector has built into it a fixed transmitter and receiver. The unit of the invention utilizes the same electronics and power supply as is usually used to protect one area, to enable adjustment to precisely aim at and cover and monitor separate areas; two transducer units, in one form of the invention, instead of one, share the single electronic circuit, all in one package. The cost of the improved unit is thus little more than that of a unit with a single set of fixed transducers; the improved unit produces twice the area volume of coverage and provides more accurate coverage thereof, at slightly more than or at the same price as that of one conventional fixed transducer unit; each set of the improved unit produces an elliptical sound energy patterns of two times 30.times.12.times.12, or a total of 60.times.12.times.12.